“…Gambusia has gained a global reputation as a pest fish species and has been implicated in the reduction or extinction of small native fish in a wide range of locations (Myers, 1965; Meffe et al., 1983; Arthington and Lloyd, 1989; Courtenay and Meffe, 1989; Lloyd, 1990; Marsh and Minckley, 1990; Lydeard and Belk, 1993; Howe et al., 1997; Gill et al., 1999; Rinco et al., 2002; Mills et al., 2004; Caiola and de Sostoa, 2005). In New Zealand, gambusia is a potential competitor with, and predator of, black mudfish, Neochanna diversus (Barrier and Hicks, 1994), and is primarily responsible for the rarity of the endemic dune lakes galaxias, Galaxias gracilis , in three Northland dune lakes, including its extinction in one of them (Rowe and Chisnall, 1997; Rowe, 2003). However, Ling (2004) reviewed the limited knowledge of its impact in New Zealand and predicted that its direct effect on native fish through competition and predation would be minimal because it occupied an under‐utilized niche (i.e.…”